Prepare to publish

Drop `-wip` suffix.
Bump upper SDK bound to silence publish warning.

PiperOrigin-RevId: 539219416

Expand pub constraint on test_api (#615)

This package is not impacted by the breaking changes, and they are already
running together internally.

Prepare to publish.

This is necessary to unblock the package roll for the flutter repository.
flutter/flutter#123350

PiperOrigin-RevId: 519012847